1. Field of the Invention
This invention relates to an image forming device having an ink-filled cartridge, an ink managing method for use in the image forming device, and an ink managing program executed by the image forming device.
2. Description of the Related Art
In an inkjet image forming device, an ink (or a printing liquid) from a printing mechanism is discharged to a printing medium so that an image is printed on the printing medium. There are two methods which are adapted for supplying the ink to the printing mechanism in the inkjet image forming device.
One method is to use an ink cartridge which is filled with an ink and attached directly to the printing mechanism in an exchangeable manner. The other is to use a subtank which is disposed on the printing mechanism and filled with an ink, and when the amount of residual ink in the subtank decreases, an ink from an ink cartridge on the body side of the image forming device is supplied to the subtank (replenishing).
In the inkjet image forming device, if the ink characteristics change due to exchange of the cartridge, preservation of the ink over an extended period of time, etc., discharging of the ink may not be performed appropriately. Various improvements are proposed in order to avoid this problem.
For example, Japanese Laid-Open Patent Application No. 2006-256005 discloses an image forming device which is adapted so that the time of performing the recovering operation of a printing head due to exchange of the ink cartridge is set to an optimal time. Japanese Patent No. 3278432 discloses an ink cartridge which is adapted so that optimal printing after exchange of the ink cartridge is easily performed and the amount of residual ink in the cartridge is detected with good accuracy.
The image forming device of the type in which the ink is supplied to the subtank has a problem that discharging of the ink from the printing mechanism may not be performed appropriately due to deterioration of the characteristics of the ink in the subtank. However, improvement for preventing inclusion of an ink of inappropriate characteristics in the subtank is not taken into consideration in the related art.